Techniques disclosed herein relate to microfabrication, and relate in particular to microfabrication of semiconductor devices.
In material processing methodologies (such as photolithography), creating patterned layers typically involves the application of a thin layer of radiation-sensitive material, such as photoresist, to an upper surface of a substrate. This radiation-sensitive material is transformed into a relief pattern that can be used as an etch mask to transfer a pattern into one or more underlying layers on the substrate. Patterning of the radiation-sensitive material generally involves exposure by a radiation source through a photomask (and associated optics) onto the radiation-sensitive material using, for example, a photolithography system. This exposure creates a latent pattern within the radiation-sensitive material in that a portion of the material is soluble and a remaining portion is insoluble to a particular developer. The radiation-sensitive material is then developed in that soluble portions are dissolved and removed to yield a relief pattern, which is a topographic or physical pattern. For example, developing can include removal of irradiated regions of the radiation-sensitive material (as in the case of positive photoresist), or non-irradiated regions (as in the case of negative resist) using a corresponding developing solvent. The resulting relief pattern can then function as a mask layer or etch mask.
Various etch techniques can be used for transferring a given relief pattern into an underlying layer. Semiconductor production equipment commonly uses dry, plasma etch processes to selectively remove material using an etching means. Once a relief pattern is formed on a substrate, the substrate is disposed within a plasma processing chamber and an etching chemistry (typically an ionizable, dissociative gas mixture) feeds a plasma such that products of the plasma selectively etch the underlying layer while minimally etching the mask layer. Microfabrication of electronic devices and components typically involves repeating steps of material deposition, pattern creation, and material removal.